Singapore Med J 2018; 59(3): 150-154 Original Article https://doi.org/10.11622/smedj.2017074

Management of computed tomography-detected in patients with : experience from a community-based hospital

Ashraf F Hefny1,2, MD, Fathima T Kunhivalappil3, MD, Nikolay Matev3, MD, Norman A Avila4, BSN, Masoud O Bashir1, MD, Fikri M Abu-Zidan2, MD, PhD

INTRODUCTION Diagnoses of pneumothorax, especially occult pneumothorax, have increased as the use of computed tomography (CT) for imaging trauma patients becomes near-routine. However, the need for chest tube insertion remains controversial. We aimed to study the management of pneumothorax detected on CT among patients with blunt trauma, including the decision for tube thoracostomy, in a community-based hospital. METHODS Chest CT scans of patients with blunt trauma treated at Al Rahba Hospital, Abu Dhabi, United Arab Emirates, from October 2010 to October 2014 were retrospectively studied. Variables studied included demography, mechanism of , endotracheal intubation, pneumothorax volume, chest tube insertion, , hospital length of stay and mortality. RESULTS CT was performed in 703 patients with blunt trauma. Overall, pneumothorax was detected on CT for 74 (10.5%) patients. Among the 65 patients for whom pneumothorax was detected before chest tube insertion, 25 (38.5%) needed chest tube insertion, while 40 (61.5%) did not. Backward stepwise likelihood regression showed that independent factors that significantly predicted chest tube insertion were endotracheal intubation (p = 0.01), non-United Arab Emirates nationality (p = 0.01) and pneumothorax volume (p = 0.03). The receiver operating characteristic curve showed that the best pneumothorax volume that predicted chest tube insertion was 30 mL. CONCLUSION Chest tube was inserted in less than half of the patients with blunt trauma for whom pneumothorax was detected on CT. Pneumothorax volume should be considered in decision-making regarding chest tube insertion. Conservative treatment may be sufficient for pneumothorax of volume < 30 mL.

Keywords: computed tomography, pneumothorax, trauma

INTRODUCTION ventilation should be administered in the patient who has In an era of rapid advances in imaging technology and resource sustained a traumatic pneumothorax until a chest tube has been constraints, more studies are needed to define the role of chest inserted”.(7) In contrast, a prospective multicentre randomised computed tomography (CT) for patients with multiple blunt controlled trial showed that in a haemodynamically stable patient, trauma. Advances in CT have greatly increased its diagnostic occult pneumothorax can be safely managed conservatively accuracy for acutely traumatised patients.(1) Recent studies have without chest tube insertion, even for mechanically ventilated demonstrated the value of chest CT for detecting chest patients.(1) We aimed to study the management of CT-detected in spite of radiation exposure and cost.(2) Thoracic injury is a pneumothorax in patients with blunt trauma, including the major cause of trauma-related death.(3) Routine use of chest CT decision to insert a chest tube, in a community-based hospital for patients with multiple trauma is preferable to selective use, as setting. it could change the course of patient management and improve outcomes.(4) METHODS Pneumothorax is the most common, potentially life- All chest CT images of patients with blunt trauma who were threatening blunt .(5) With the near-routine use of CT treated at Al Rahba Hospital, Abu Dhabi, during a four-year for imaging in patients with multiple trauma, the diagnosis of period from October 2010 to October 2014 were retrospectively pneumothorax has increased.(1) This is particularly so for occult studied. Al Rahba Hospital is a community-based hospital, with pneumothorax, which is not detected on initial chest radiography. a capacity of 190 beds, located on the main highway connecting However, the need for chest tube insertion, which is an invasive Abu Dhabi and Dubai cities. About 700 patients with multiple procedure, for the management of small pneumothorax remains trauma are admitted to the hospital annually. controversial, especially for patients with occult pneumothorax.(6) Variables studied included demography, mechanism of injury, According to Advanced Trauma Life Support (ATLS) endotracheal intubation and mechanical ventilation, the need for guidelines, “Any traumatic pneumothorax is best treated with chest tube insertion, Injury Severity Score (ISS), Glasgow Coma a chest tube. Neither general anaesthesia nor positive-pressure Scale (GCS) score, Revised Trauma Score, hospital length of stay

1Department of Surgery, Al Rahba Hospital, Abu Dhabi, 2Department of Surgery, College of Medicine and Health Sciences, UAE University, Al-Ain, 3Department of Radiology, 4Trauma Registry Program, Al Rahba Hospital, Abu Dhabi, United Arab Emirates Correspondence: Dr Ashraf F Hefny, Assistant Professor, Trauma Group, Department of Surgery, College of Medicine and Health Sciences, UAE University, PO Box 18532 Main Building of Post Office, Al-Ain, United Arab Emirates. [email protected]

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and mortality. For patients who needed chest drainage, a chest 74 patients with pneumothorax on CT tube of size 28–32 French was usually inserted using the open technique at the fifth intercostal space. Antibiotics were not routinely administered. Clinical examination CT was performed using a General Electric 64-slice LightSpeed Volume (GE 64-slice LightSpeed VCT; General Electric, Boston, MA, USA). All patients underwent scanning of the entire thorax as Yes No Chest tube part of trauma CT. Images were analysed in the lung, mediastinal and bone windows at 2.5-mm thick axial cuts. CT images with 2 72 pneumothorax were further analysed in the coronal and sagittal planes. The images were reviewed to determine the size of Yes No Chest pneumothorax. The volume of pneumothorax was calculated in radiography millilitres (mL) using the manual segmentation method (software 40 32 available in the CT machine). Radiological images (including chest radiographs and CT images) were independently reviewed by two Yes No Chest radiologists. Patients with bilateral pneumothorax were analysed tube as one patient with two hemithoraces positive for pneumothorax. 7 33 The volume of pneumothorax in patients having bilateral pneumothorax was calculated by adding up the pneumothorax volumes in the two hemithoraces. The number of trauma patients who were treated in the Chest CT Chest CT emergency department and the number of trauma patients admitted were retrieved from the hospital’s trauma registry. The Al

Rahba Hospital Research Ethics Committee approved the research Yes No 27 Yes Chest No Chest project (ARH/REC-040). tube tube Non-parametric methods were used to compare the two independent groups due to the small number of patients 13 20 12 20 recruited in the study.(8) Fisher’s exact test was used to compare Fig. 1 Management algorithm of patients with blunt trauma (n = 74) for categorical variables, while Mann-Whitney U test was used to whom pneumothorax was detected on computed tomography (CT). compare continuous or ordinal variables. Univariate analysis was used to compare patients with and without chest tube insertion Table I. Radiological findings of patients with and without chest subsequent to CT. Factors with p < 0.1 were then entered into a tube insertion after undergoing chest radiography following clinical examination. backward stepwise likelihood regression model. A p ≤ 0.05 in the model was considered statistically significant. Data was analysed Finding No. (%) p‑value* with IBM SPSS Statistics version 20 (IBM Corp, Armonk, NY, USA). Chest tube No chest tube insertion insertion (n = 20) (n = 20) RESULTS Normal 2 (10.0) 7 (35.0) 0.13 During the study period, 25,628 trauma patients were treated in Pneumothorax 9 (45.0) 1 (5.0) 0.008 the emergency department, among whom 2,860 (11.2%) patients Haemothorax 3 (15.0) 4 (20.0) 0.99 were admitted to the hospital. Fractured ribs 12 (60.0) 9 (45.0) 0.53 Chest CT was performed for 703 patients with blunt trauma. Lung contusion 7 (35.0) 6 (30.0) 0.99 Among these, pneumothorax was detected in 74 (10.5%) patients Subcutaneous 5 (25.0) 2 (10.0) 0.41 and all of them were admitted to the hospital. Of these 74 patients, emphysema 15 (20.3%) had bilateral pneumothorax and 63 (85.1%) were men. Patients could have more than one finding on chest radiography. *p‑values were The median age of the patients was 30 (range 11–74) years. Median calculated using Fisher’s exact test. ISS and GCS scores were 18 (range 8–45) and 15 (range 3–15), respectively. The most common mechanisms of injury were road on chest radiography and one patient, who was mechanically traffic collision (n = 63, 85.1%) and fall from height (n = 7, 9.5%). ventilated and had rib fractures on chest radiography, had the Among the 74 patients, chest radiography was performed chest tube inserted prophylactically. prior to CT for 40 (54.1%) patients (Fig. 1). Overall, 9 (12.2%) Table I compares the radiological findings of chest radiography patients needed chest tube insertion before CT. For two patients that was performed following the initial clinical examination with obvious tension pneumothorax on clinical examination, the between patients with (n = 20) and without (n = 20) chest tube chest tube was inserted prior to chest radiography. For another insertion. In the former group, chest tube insertion occurred seven patients, the chest tube was inserted prior to CT but after before CT for seven patients and after CT for 13 patients. The chest radiography. Among these, six patients had pneumothorax only statistically significant difference between patients with and

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Table II. Univariate analysis of patients with and without chest tube insertion after pneumothorax was detected on CT.

Variable No. (%) p‑value Chest tube insertion (n = 25) No chest tube insertion (n = 40) Age (yr)*,† 29.0 (18–58) 33.5 (11–74) 0.58 Gender 0.18 Men 23 (92.0) 31 (77.5) Women 2 (8.0) 9 (22.5) Nationality 0.06 UAE 5 (20.0) 18 (45.0) Non‑UAE 20 (80.0) 22 (55.0) Heart rate (beats/min)*,† 118.0 (80–135) 94.5 (62–164) 0.01 Mean systolic BP (mmHg)*,† 127.5 (66–190) 128.5 (47–187) 0.95 GCS*,† 15 (3–15) 15 (3–15) 0.02 ISS*,† 25 (10–45) 17 (8–34) 0.004 Respiratory rate*,† 21.5 (0–48) 22.0 (11–40) 0.52 RTS*,† 12 (8–12) 12 (6–12) 0.11 Mechanism 0.96 Road traffic collision 23 (92.0) 34 (85.0) Fall 1 (4.0) 4 (10.0) Other 1 (4.0) 2 (5.0) Endotracheal intubation 13 (52.0) 9 (22.5) 0.018 Fractured ribs 19 (76.0) 27 (67.5) 0.58 ICU admission 14 (56.0) 10 (25.0) 0.017 Hospital length of stay 11 (1–105) 4 (1–46) 0.001 Pneumothorax volume (mL)*,‡ 114.2 (0.11–1,408.00) 12.0 (0.20–148.00) 0.001 Patients for whom chest tube was inserted prior to CT (n = 9) were excluded from the analysis. *Data presented as median (range). †p‑values were calculated using Fisher’s exact test or Mann‑Whitney U test, as appropriate. ‡Volume of pneumothorax in both hemithoraces for each patient. BP: blood pressure; CT: computed tomography; GCS: Glasgow Coma Scale score; ICU: intensive care unit; ISS: Injury Severity Score; RTS: Revised Trauma Score; UAE: United Arab Emirates

Table III. Factors predicting chest tube insertion after CT based on backward likelihood logistic regression analysis.

Variable β Standard error Wald test p‑value OR (95% CI) Non‑UAE nationality −3.700 1.43 6.72 0.01 0.03 (0.001–0.410) Endotracheal intubation 3.120 1.23 6.41 0.01 22.65 (2.02–253.63) Pneumothorax volume 0.017 0.01 4.66 0.03 1.02 (1.00–1.03) Heart rate 0.040 0.02 3.70 0.05 1.04 (0.99–1.08) Constant −5.190 2.03 6.53 0.01 0.006

CI: confidence interval; OR: odds ratio; UAE: United Arab Emirates without chest tube insertion was the detection of pneumothorax groups showed that patients with chest tube had significantly on chest radiography (p = 0.008 using Fisher’s exact test). higher heart rate (p = 0.01), lower GCS score (p = 0.02), higher Chest radiography showed overt pneumothorax in only injury severity (p = 0.004), more intensive care unit admission 10 (25.0%) out of 40 patients: six had chest tube insertion before (p = 0.017) and higher need for endotracheal intubation CT, three had chest tube insertion after CT and one had no chest (p = 0.018). Patients who needed chest tubes had significantly tube insertion. 30 (75.0%) patients had occult pneumothorax higher pneumothorax volume (p = 0.001) and hospital length of (i.e. pneumothorax not detected by chest radiography), which was stay (p = 0.001). There was a trend towards chest tube insertion detected by CT. Among these patients, 11 (36.7%) had chest tube among non-UAE citizens, but this was not statistically significant insertion and 19 (63.3%) did not. The median volume of occult (p = 0.06). pneumothorax on CT was 12.7 (range 0.11–1,401.00) mL. As chest Factors with p < 0.1 on univariate analysis were entered into tube insertion can change the exact volume of pneumothorax on a backward stepwise likelihood regression model (Table III). The subsequent CT, patients with chest tube insertion were excluded model was highly significant (p < 0.0001), with a Nagelkerke 2R from the logistic regression analysis. of 0.6. Independent factors that significantly predicted chest tube Overall, pneumothorax was detected on CT in 65 patients insertion among patients with blunt trauma were endotracheal without prior chest tube insertion. Among these, chest tube was intubation (p = 0.01), non-UAE nationality (p = 0.01) and inserted after CT for 25 (38.5%) patients and not inserted for 40 pneumothorax volume (p = 0.03). The receiver operating (61.5%) patients (Table II). Univariate comparison of these two characteristic (ROC) curve showed that the best pneumothorax

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1.0 tube insertion for haemothorax or pneumothorax, mechanical ventilation or surgery.(2) CT is more sensitive and specific when compared to chest radiography and significantly reduces the time for patient management in emergency departments.(12) In 0.8 our study, chest radiography was not performed for 45.9% of patients, who were sent directly for trauma CT. This reflects the new trend over recent years of sending stable trauma patients 0.6 for trauma CT immediately in order to save time and for more accurate diagnosis.(12,13)

Sensitivit y The clinical importance and proper management of 0.4 pneumothorax detected on CT in patients with blunt trauma remains controversial.(14,15) In our study, pneumothorax was detected on CT among 10.5% of patients with blunt trauma, with 0.2 20.3% of these patients having bilateral pneumothorax. The most common mechanism of injury among our patients was road traffic collisions, similar to the findings of Mennicke et al.(5) As in other 0.0 0.0 0.2 0.4 0.6 0.8 1.0 studies, 75.0% of patients who underwent chest radiography in our 1 - Specificity study did not have clear evidence of pneumothorax on radiography although it was detected on subsequent CT. In these patients, Fig. 2 Receiver operating characteristic curve for the best pneumothorax volume (mL) that predicted chest tube insertion for patients in whom pneumothorax might not have been diagnosed if CT had not been pneumothorax was detected on computed tomography. performed, persisting as occult pneumothorax instead.(16,17) In all, 19 (63.3%) out of 30 patients were treated conservatively without volume that predicted chest tube insertion was 30 mL (sensitivity chest tube insertion in our study. Other studies have reported 72%, specificity 72%, area under the curve 75%; Fig. 2). that 48% of patients with occult pneumothorax were treated Overall, 34 (45.9%) patients had chest tube insertion and conservatively.(3) In comparison, we adopted a more conservative 40 (54.1%) patients did not, instead receiving conservative approach. None of our patients who were treated conservatively treatment. There was no increase in the size of pneumothorax needed a chest tube insertion subsequently. among patients who were treated conservatively following CT. Similar to other studies, neither nor These patients did not need any chest tube insertion for treatment rib fractures on chest radiography were significantly associated of the pneumothorax. The median duration of chest tube insertion with chest tube insertion in our patients.(18,19) On the other hand, was 3 (range 1–7) days. 30 (40.5%) patients were admitted to finding overt pneumothorax on chest radiography was significantly the intensive care unit. Intubation and mechanical ventilation associated with chest tube insertion even prior to performing CT. were needed for 28 (37.8%) patients. The mean hospital length This might be due to concerns among physicians of the possible of stay was 9.8 (range 1–105) days. Five patients died, giving an development of tension pneumothorax during CT. In our study, overall mortality of 6.8%. CT was performed immediately after stabilisation of the patient and insertion of chest tube to detect other associated injuries. As DISCUSSION the chest tube insertion may have resulted in mild pneumothorax Initial evaluation and treatment of our patients was based on that would not be picked up during subsequent CT, we did not ATLS principles. Supplemental imaging for stable patients with include these patients in the logistic regression analysis. blunt trauma usually involves chest radiography as an adjunct Our study showed that endotracheal intubation and to the primary survey and subsequent trauma CT as an adjunct pneumothorax volume were independent factors that significantly to the secondary survey.(7) predicted chest tube insertion.(3,19) ATLS training is mandatory for While supine chest radiography cannot detect occult all trauma surgeons and emergency physicians in our hospital, who pneumothorax, supine oblique chest radiography may be as were likely to have followed the ATLS guidelines mandating chest good as lung ultrasonography for the detection of large occult tube insertion for intubated patients with traumatic pneumothorax.(7) pneumothorax.(9) However, if supine radiography of the chest Chest drainage of mechanically ventilated patients with shows abnormal findings, then the risk of chest injuries is traumatic pneumothorax is controversial. Kirkpatrick et al have considerably high.(10) In a single-blind prospective clinical shown that the size of the pneumothorax is not important for chest study, chest ultrasonography was more reliable for early tube insertion, while the need for prolonged ventilator support bedside diagnosis of pneumothorax compared with supine chest is.(1) In contrast, other studies have shown that chest tube drainage radiography.(11) is required when the size of the pneumothorax is ≥ 16 mm thick. Langdrof et al have shown, in a multicentre prospective study, The need for positive pressure ventilation alone does not justify that 71% of chest injuries would be missed if chest radiography chest drainage.(19) Charbit et al have shown that 6% of patients was done without chest CT for occult injuries and that 14% of these with severe trauma had large occult pneumothorax (> 30 mm occult injuries would need major interventions, including chest thick), which was not detected by chest radiography. The

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